This invention relates to fibers formed from α(1→3) polysaccharides, and to methods of producing said fibers. More particularly, this invention relates to fiber spinning solutions comprising α(1→3) polysaccharides using ionic liquids as solvents.
Cellulose, a polysaccharide consisting of β(1→4)-linked glucose, formed by natural processes, (Applied Fiber Science, F. Happey, Ed., Chapter 8, E. Atkins, Academic Press, New York, 1979) has become the preeminent fiber for use in manufactured textiles, films and resins. Cotton, an especially pure form of naturally occurring cellulose, is well-known for its beneficial attributes in textile applications.
Cellulosic fibers such as cotton and rayon increasingly present sustainability issues with respect to land use and environmental imprint. This may be a significant factor leading to increased level of research into textiles containing polyester fiber blends with cellulosic materials and more sustainable solutions for cellulosic-derived materials. It can be desirable to produce fibers and other cellulosic materials using other glucose-based polysaccharides—for example in films, fibers and resins that can be economically produced from renewable resources. In addition it can be desirable to produce such products using materials that are benign in the environment.
Poly (α(1→3) glucan), a glucan polymer characterized by having α(1→3) glycoside linkages, has been isolated by contacting an aqueous solution of sucrose with a glycosyltransferase (gtfJ) enzyme isolated from Streptococcus salivarius (Simpson et al., Microbiology, 141: 1451-1460, 1995). Poly (α(1→3) glucan) refers to a polysaccharide composed of D-glucose monomers linked by glycosidic bonds. Films prepared from poly (α(1→3) glucan) tolerate temperatures up to 150° C. and provide an advantage over polymers obtained from β(1→4) linked polysaccharides (Ogawa et al., Fiber Differentiation Methods, 47: 353-362, 1980).
U.S. Pat. No. 7,000,000 disclosed preparation of a polysaccharide fiber comprising hexose units, wherein at least 50% of the hexose units within the polymer were linked via (α(1→3) glycoside linkages using the gtfJ enzyme. The gtfJ enzyme utilizes sucrose as a substrate in a polymerization reaction producing poly (α(1→3) glucan) and fructose as end-products (Simpson et al., et al., Microbiology, 141: 1451-1460, 1995).
U.S. Pat. No. 7,000,000 discloses a process for preparing fiber from liquid crystalline solutions of acetylated poly(α(1→3) glucan). Thus prepared fiber was then de-acetylated resulting in a fiber of poly(α(1→3) glucan).
WO2011056924 discloses the use of combinations of ionic liquids as solvents for certain polymers, including biopolymers and synthetic polymers. Ionic liquids can be desirable as solvents because of their benign environmental impact, ease of processing, cost, and other potential benefits.
Rogers, in the Journal of the American Chemical Society (J. Am. Chem. Soc., Vol. 124, 4974-4975 (2002)) and Cai in the Journal of Applied Polymer Science (Journal of Applied Polymer Science, Vol. 115, 1047-1053 (2010)) describe ionic liquid solutions of cellulose.
While poly(α(1→3) glucan) and cellulosic polymers are similar in many aspects, poly(α(1→3) glucan) does not exhibit the same solubility behavior as cellulosic polymers in ionic liquids.
It can be desirable to provide ionic liquid solutions of poly(α(1→3) glucan) for use in industrial processes, wherein the glucan fiber does not require a further deacylation of the fiber. Further, it can be desirable to provide solutions of poly(α(1→3) glucan) using ionic liquids as solvents, but wherein the poly(α(1→3) glucan) can be recovered from the solution in a fiber spinning operation.